(a) Field of the Invention
The present invention relates to a polarization beamforming communication method and apparatus.
(b) Description of the Related Art
The attenuation of a transmission loss in a millimeter wave band is 100 times or more that of a transmission loss in a common microwave band. For example, the attenuation of a signal of a 60 GHz band is about 144 times greater than that of a signal of a 5 GHz band. Accordingly, in the millimeter wave band, a signal is transmitted to a target terminal with maximum power. For this reason, a technology for forming a beam having a narrow width using many antennas and transmitting the beam has been in the spotlight as a prospect technology in the millimeter wave band. Furthermore, the use of a beam having a narrow width in the millimeter wave band results in a communication environment in which a line-of-sight including a very small number of reflection waves due to the narrow beam width is dominant.
Polarization indicates a polarity generated by an electric field on a plane perpendicular to the axis in which an electromagnetic wave travels when the electromagnetic wave travels. Maximum energy may be transmitted when the polarization of a transmission stage is fully identical with that of a reception stage. If the polarization of the transmission stage is orthogonal to that of the reception stage, most transmission energy is unable to be transmitted to the reception stage. Furthermore, if vertical and horizontal dual polarization antennas orthogonal to each other are used in the transmission stage and the vertical and horizontal antennas are made to have the same RF path, various transmission polarizations may be generated through signal processing in the baseband.
In general, in a communication environment in which polarization is changed in a reflected wave and a line-of-sight is dominant, a technology for matching transmission polarization with reception polarization is very important in order to improve transmission efficiency because a reflected wave is rarely present.